(1) Field of the Invention
This invention relates to injection molding machines, and more particularly to mechanisms for successively loading particular quantities of material into the injection unit of an injection molding machine.
(2) Prior Art
The feeding of plastic-like material in measured quantities to machines for subsequent processing, has taken a number of forms, such as the U.S. Pat. No. 2,383,536 to Elliott, showing a dough dividing machine, where a reciprocating plunger in a measuring chamber is arranged in a hopper, to discharge a slug of dough. The plunger is adjusted by means of a screw which limits its travel distance. The cycle time is limited because the dough must flow into the measuring chamber before the plunger can move to charge it. Another interesting device for molding plastic materials comprises a rotatable turntable having a plurality of openings therein, which passes under a hopper to receive material therein, and rotates to a position to eject an edible cake formed in the opening, for subsequent processing.
U.S. Pat. No. 3,421,220 to Stanga shows an apparatus for forming and molding cheese wherein empty cheese formers ride a turntable and cheese is pushed up into them. The formers rotate to a position where they are unclamped and removed by hand. The rotational aspect is efficient, but hand removal is inefficient.
A further U.S. Pat. No. 4,003,498 to Moneghan discloses an apparatus wherein bulk material is fed to a plasticizing screw from an overhead stuffer hopper by a reciprocating plunger. The screw is operable during injection periods to fill mold halves to make brake shoes and the like. The screw is stoppable during press portions of the cycle, by de-actuation thereof, through complicated electrical circuitry. The prior art also includes U.S. Pat. Nos. 3,979,488 to Greenhalgh et al and 4,168,943 to Abraham which show screw feed mechanisms for continuous screw extruders, the former having a reciprocating screw to assist in the material supply process. The art uncovered discloses these various feed mechanism which are rather elaborate and/or inefficient for accomplishing a consecutive feed operation of measured units of material to an injection molding machine.
It is thus an object of the present invention, to provide an apparatus for overcoming the disadvantages of the prior art.
It is also an object of the present invention to provide an apparatus which will consecutively feed measured amounts of plastic-like material, to an injection molding machine in an efficient and simple manner.